In general, LED based lighting applications are powered from a lighting grid via a so-called LED driver or ballast. Such an LED driver or ballast can e.g. comprise a Buck or Boost power converter or the like.
LED based lighting applications often comprise a plurality of LED fixture (or LED engine) which can be independently controlled or adjusted by a user (via one or more user interfaces). Therefore, LED based lighting applications may, in general, comprise a plurality of LED drivers or ballasts for powering the plurality of LED fixtures. Typically, an LED driver for powering an LED fixture may comprise a power converter (converting an input power such as obtained from a mains supply to an output power suitable for powering the LED fixture) and a control unit for controlling the power converter. As an example, the control unit can e.g. control an output characteristic of the power converter (e.g. a current level of the output power) based on an input signal received from a user interface.
As LED fixtures in general allow for a variety of illumination parameters to be adjusted, a (digital) communication system is often provided between the plurality of LED drivers and user interfaces. Examples of such systems can e.g. comprise communication busses using DALI or 1-10V protocols. As such, an LED based lighting application can in general comprise a plurality of LED fixtures, which can e.g. be powered by a plurality of LED drivers (e.g. connectable to a mains power supply), and one or more user interfaces, the LED drivers and/or LED fixtures and user interfaces being connected by a communication bus such as a DALI communication bus. The communication between the various components connected to the communication bus can e.g. be controlled by a (master) control unit connected to the bus. Such a master control unit, such as a DALI master may also be used to configure the lighting application.
The LED fixture may be exchangeable and form a separate module that may be connected to the LED driver. Such exchangeability may provide a problem with reproducibility of intensities, colors and other characteristics of the lighting application as a whole. For example neighboring fixtures may have aged and have lower intensity at nominal current than the exchanged fixture